Cold Climates May Lead to More Obesity-Related Gut Bacteria

Date Posted:
1/6/2015 11:15:18 AM

A meta-analysis has found that people who live in colder, northern climates may have more of the gut bacteria that is thought to be associated with obesity.

The meta-analysis, which was published in February 2014 in Biology Letters, included six studies encompassing 1,020 people living in 23 different populations in North and South America, Europe, Africa, and Asia.

The impetus behind the meta-analysis was Bergmann’s Rule, which observes that humans have adapted to colder climates by increasing their body mass. With that in mind, the researchers decided to test whether the gut bacteria associated with obesity is more notable in northern populations.

They were surprised to find that, indeed, the six studies showed that Firmicutes bacterial numbers increased with latitude, while Bacteroidetes decreased. This was true even when the researchers adjusted for age, sex and bacterial detection methods.

“Comparisons between African Americans and native Africans and between European Americans and native Europeans suggest no evidence of host genotype explaining the observed patterns,” the researchers wrote.

The researchers noted that Bergmann’s Rule shows that obesity may not have necessarily been a detriment in the past, when fat and energy from the diet might have been important to survival in colder temperatures.

“This suggests that what we call ‘healthy microbiota’ may differ in different geographic regions. Our gut microbes today might be influenced by our ancestors,” they wrote. “This surprising link between large-scale geography and human gut microbial composition merits further investigation.”